Near Field Coupling Devices and Associated Systems and Methods

ABSTRACT

A near-field coupling device that may facilitate communications with a transponder is provided. The near-field coupling device may include a ground plane, a dielectric substrate, one or more conductive strips and a terminating load. The conductive strips together with the ground planes form coupling elements. The near-field coupling device further includes one or more switching elements for selectively connecting and disconnecting the coupling elements with a transceiver. The connected coupling elements define a total characteristic impedance. Using the switching element, the ratio between the total characteristic impedance of the connected coupling elements and the terminating load may be changed in order to adjust the distribution of an electromagnetic field along the coupling elements according to the type and position of the transponder to be processed.

BACKGROUND

1. Field of the Invention

The present invention relates to RFID (Radio Frequency Identification)systems and, in particular, to near field antennas for such systemsconfigured to selectively communicate with a targeted RFID transponderfrom among a group of adjacent transponders.

2. Description of Related Art

RFID technology is rapidly becoming essential to not only accuratelymanage assets and inventory, but also in a variety of other practicalapplications. With respect to inventory applications, RFID tags, alsoknown as transponders, are being used to count and identify inventory inretail stores, warehouses, shipping containers, and the like, to allowfor more accurate bookkeeping and ordering of replacement orreplenishment goods. Moreover, it has been determined that many otherapplications for RFID technologies are becoming increasingly beneficialand/or economical. For example, RFID transponders are being used insecurity applications to grant individuals access to secure areas. RFIDtransponders are also being used in vehicles to pay tolls whilemaintaining vehicle speeds. Further, RFID transponders are even beingimplanted in pets to allow for accurate identification of a pet in theevent that the pet is lost. As such, RFID technology is becomingubiquitous in a wide variety of applications, and new applications forthe technology are being developed continuously.

A conventional RFID system provides for wireless data acquisitionfrom/to transponders to/from a transceiver. In various applications, thetransponders may be active (e.g., battery-powered, battery-assisted, orbattery supported) or passive (e.g., activated by an RF field). Aconventional transponder includes an antenna that facilitates thereception of communications from the transceiver. In order to encode(e.g., read, write), the transceiver through an antenna of thetransceiver exposes the transponder to a radio frequency (RF)electromagnetic field or signal. In the case of a passive UHFtransponder, the RF electromagnetic field energizes the transponder andthereby enables the transponder to respond to the transceiver byre-radiating the received signal back and modulating the field in awell-known technique called backscattering. In the case of an activetransponder, the transponder may respond to the electromagnetic field bytransmitting an independently powered reply signal to the transceiver.In this manner, various applications for RFID technology may beimplemented.

Some RFID applications utilize transponders that may be encoded prior toutilization within a system. In this regard, a transponder may beencoded by communicating commands and/or data to a transponder such as,for example, a unique identifier. The transponders may be encoded in anumber of ways. In some instances, a printer may be configured with aspecialized printhead or other apparatus (e.g., a printer-encoder) thatmay be utilized to encode the transponders. The encoding process caninvolve magnetic coupling the transponder to the printer-encoder throughan antenna of the printer-encoder such that commands or data aretransmitted to the transponder to facilitate the encoding process. Someconventional printer-encoders can encode transponders that are affixedto or embedded on a media, such as a smart label or a tag. When themedia passes through the printer-encoder, the printer-encoder isconfigured to encode the transponders affixed to the media such that thetransponders may be later used in connection with other RFID systems andapplications.

However, in some instances, errors in the encoding process (e.g.,improperly encoded transponders or encoding failures) can occur due tothe variations of the justification and type of transponders to beencoded. Justification refers to the location of the transponderrelative to the antenna or other reference point of a printer-encoder.The encoding errors largely arise from non-uniform location ororientation of the transponder on the media received by aprinter-encoder. As a result, the location of the transponders relativeto the antenna of the printer-encoder may be unpredictable, and theelectromagnetic field generated by the antenna of the printer-encodermay not be effective for encoding of the transponders. As such, it maybe desirable to develop and implement a system and antenna that canaccount for the unpredictability of the positioning of a transponderrelative to the near-field coupling device.

BRIEF SUMMARY

Accordingly, exemplary embodiments of the present invention provide fora dynamic near-field coupling device that may be configured toadaptively change coupling strength and relative coupling position. Insome embodiments, the near-field coupling device may be included in aprinter-encoder to provide for encoding of transponders. According tovarious exemplary embodiments, a near-field coupling device may includeone or more conductive strips and a terminating load. The near-fieldcoupling device may also include various means for adaptively changingthe coupling strength and relative coupling position, such as, forexample, via switching devices. In some exemplary embodiments, thepattern of the electromagnetic field produced by the near-field couplingdevice may be generated by selecting a ratio of a total characteristicimpedance of one or more coupling elements to the terminating loadimpedance. In some embodiments, the ratio may be selected such that thetotal characteristic impedance of the coupling elements is greater thanor less than the terminating load.

For example, according to an embodiment of the present invention, anear-field coupling device for coupling a transceiver with a targetedtransponder is provided. The near field coupler device includes a groundplane, a dielectric substrate, a terminating load, a first conductivestrip, a second conductive strip, and a switching element. Thedielectric substrate is adjacent to the ground plane. The firstconductive strip is adjacent the dielectric substrate, extends from aport end to a loaded end, and is connected to the terminating load. Thefirst conductive strip and the ground plane form a first couplingelement having a length of one half-wavelength or multiple thereof. Thesecond conductive strip is adjacent the dielectric substrate, extendsfrom the port end to the loaded end, and is connected to the terminatingload. The second conductive strip and the ground plane form a secondcoupling element having a length of one half-wavelength or multiplethereof. The switching element is for selectively electricallyconnecting one or more of the first and second coupling elements withthe transceiver. The connected coupling elements define a totalcharacteristic impedance of the connected coupling elements. In a firstconfiguration of the switching element, the total characteristicimpedance of the connected coupling elements is greater than theterminating load. In a second configuration of the switching element,the total characteristic impedance of the connected coupling elements isless than the terminating load.

The impedances of the coupling elements relative to each other may vary.As examples, an impedance of the first coupling element, in isolation,may be approximately equal to or greater than an impedance of the secondcoupling element, in isolation. As further examples, a width of thefirst conductive strip may be approximately equal to or greater than awidth of the second conductive strip.

The near-field coupling device may further include one or moreadditional conductive strips. Each additional conductive strip may forman additional coupling element having a length of one half-wavelength ormultiple thereof. The switching element may be further configured toselectively connect the additional coupling elements and further adjustthe total characteristic impedance of the connected coupling elements.

Each of the first and second conductive strips may define a linear shapeand may be parallel to the other conductive strip.

The first and second conductive strips may be configured to generate anelectromagnetic field and are capable of activating the targetedtransponder as the targeted transponder moves through theelectromagnetic field.

In another embodiment, an apparatus comprising a processor is provided.The processor may be configured to receive indications of a transpondertype and a transponder position justification; and connect one or morecoupling elements of a near-field coupling device depending on at leastthe transponder type and the transponder position justification toconfigure a total characteristic impedance of the coupling elementsrelative to a terminating load of the near-field coupling device.

The processor configured to connect the one or more coupling elementsmay further include being configured to connect the one or more couplingelements to configure the total characteristic impedance of the couplingelements to be greater than or less than the terminating load. Forexample, the processor configured to connect the one or more couplingelements may include being configured to connect the one or morecoupling elements to configure the total characteristic impedance of thecoupling elements to be greater than the terminating impedance when thetransponder type describes a loop-type transponder and the transponderposition justification is edge justified.

The processor configured to connect the one or more coupling elementsmay further include being configured to connect the one or more couplingelements by controlling a respective switching device associated withthe one or more coupling elements.

The processor may further be configured to encode one or moretransponders by providing for transmission of a signal to a port of thenear-field coupling device.

According to yet another embodiment, a method is provided. The methodmay include receiving indications of a transponder type and atransponder position justification; and connecting one or more couplingelements of a near-field coupling device based on at least thetransponder type and the transponder position justification to configurea total characteristic impedance of the coupling elements relative to aterminating load of the near-field coupling device.

The operation of connecting the one or more coupling elements mayinclude connecting the one or more coupling elements to configure thetotal characteristic impedance of the coupling elements of thenear-field coupling device to be greater than or less than theterminating load. For example, connecting the one or more couplingelements may include connecting the one or more coupling elements toconfigure the total characteristic impedance of the coupling elements tobe greater than the terminating load when the transponder type is aloop-type transponder and the transponder position justification is edgejustified.

The operation of connecting the one or more coupling elements mayincludes being configured to connect the one or more coupling elementsby controlling a respective switching device associated with the one ormore coupling elements.

The method may further include encoding one or more transponders byproviding for transmission of a signal to a port of the near-fieldcoupling device.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

FIG. 1 illustrates a side schematic view of a printer-encoder accordingto an exemplary embodiment of the present invention;

FIG. 2 illustrates a side view of a feed path of media units in aprinter-encoder consistent with an exemplary embodiment of the presentinvention;

FIG. 3 a illustrates an example of a long and narrow dipole-typetransponder consistent with an exemplary embodiment of the presentinvention;

FIG. 3 b illustrates another example of a long and narrow dipole-typetransponder consistent with an exemplary embodiment of the presentinvention;

FIG. 3 c illustrates another example of a long and narrow dipole-typetransponder consistent with an exemplary embodiment of the presentinvention;

FIG. 3 d illustrates another example of a long and narrow dipole-typetransponder consistent with an exemplary embodiment of the presentinvention;

FIG. 3 e illustrates an example of a long and wide two port ICdipole-type transponder consistent with an exemplary embodiment of thepresent invention;

FIG. 3 f illustrates another example of a long and wide port ICdipole-type transponder consistent with an exemplary embodiment of thepresent invention;

FIG. 4 a illustrates an example of a small loop-type transponderconsistent with an exemplary embodiment of the present invention;

FIG. 4 b illustrates another example of a small loop-type transponderconsistent with an exemplary embodiment of the present invention;

FIG. 4 c illustrates an another example of a small loop-type transponderconsistent with an exemplary embodiment of the present invention;

FIG. 4 d illustrates an another example of a small loop-type transponderconsistent with an exemplary embodiment of the present invention;

FIG. 4 e illustrates an another example of a small loop-type transponderconsistent with an exemplary embodiment of the present invention;

FIG. 4 f illustrates yet another example of a small loop-typetransponder consistent with an exemplary embodiment of the presentinvention;

FIG. 5 a illustrates a schematic of a near-field coupling deviceaccording to an exemplary embodiment of the present invention;

FIG. 5 b illustrates a schematic of another coupling device according toan exemplary embodiment of the present invention;

FIG. 5 c illustrates a schematic of another coupling device according toan exemplary embodiment of the present invention;

FIG. 5 d illustrates a schematic of another coupling device according toan exemplary embodiment of the present invention;

FIG. 6 a is a graphical illustration of the current distribution alongthe length of a dipole-type antenna;

FIG. 6 b is an illustration of the magnetic and electric field strengthdistribution of a dipole-type antenna;

FIG. 7 a is an illustration simulated on Ansoft HFSS software ofmagnetic field distribution where the maximum field strength is locatednear the center of a half wavelength coupling device with acharacteristic impedance lower than a terminating load impedanceaccording to an exemplary embodiment of the present invention;

FIG. 7 b is a graphical illustration simulated on Ansoft HFSS softwareof the magnetic and electric field strength along a half wavelengthcoupling device with a characteristic impedance larger than aterminating load impedance according to an exemplary embodiment of thepresent invention;

FIG. 7 c is an illustration simulated on Ansoft HFSS software of themagnetic field distribution where the maximum magnetic field strength islocated near the longitudinal edges of a half wavelength coupling devicewith a characteristic impedance larger than a terminating load impedanceaccording to an exemplary embodiment of the present invention;

FIG. 8 is an illustration of an overhead view of the feed path of anedge justified web according to an exemplary embodiment of the presentinvention;

FIG. 9 is an illustration of an overhead view of the feed path of acenter justified web according to an exemplary embodiment of the presentinvention; and

FIG. 10 illustrates a schematic of a near-field coupling deviceconsistent with another exemplary embodiment of the present invention

DETAILED DESCRIPTION

The present invention now will be described more fully hereinafter withreference to the accompanying drawings, in which some, but not allembodiments of the invention are shown. Indeed, this invention may beembodied in many different forms and should not be construed as limitedto the embodiments set forth herein; rather, these embodiments areprovided so that this disclosure will satisfy applicable legalrequirements. Like numbers refer to like elements throughout. The term“exemplary,” as used herein, is not provided to convey any qualitativeassessment, but is used instead to merely convey an illustration of anexample.

Exemplary embodiments of the present invention concern an apparatus forenabling an RFID transceiver to communicate with a transponder that maybe commingled among or positioned in close proximity to multipleadjacent transponders. As will be apparent to one of ordinary skill inthe art, various exemplary embodiments of the present invention aredescribed below that communicate with a targeted transponder, in someinstances, requiring little to no electromagnetic isolation of thetransponder. However, some exemplary embodiments of the presentinvention may make use of, for example, space-consuming shieldedhousings, anechoic chambers, or relatively more complex, time consuming,or costly collision management techniques.

Several exemplary embodiments of the present invention may be useful forencoding (e.g., reading or writing actions) to passive or activetransponders attached to, for example, portions of media being fedthrough a printer-encoder, items on an assembly line or in an inventorymanagement center, or in various other circumstances, includingcircumstances where the transponders are in close proximity to eachother. In various embodiments, one or more transponders may be mountedto, or embedded within a portion of a media, such as a label, ticket,card, other media forms, or the like that may be carried on a liner orcarrier. In alternate linerless embodiments, a liner or carrier may notbe needed. Such RFID enabled labels, tickets, tags, other media forms,or the like are referred to collectively herein as “media units,” “smartmedia units,” or “RFID smart cards.” As will be apparent to one ofordinary skill in the art, it may be desirable to print indicia such astext, numbers, barcodes, graphics, etc., to such media units before,after, or during communications with their corresponding transponders.

An example of an RFID system that may benefit from one or more of theembodiments of the present invention is a RFID enabled printer system,also referred to herein as a “printer-encoder” or a RFID print-engineapplicators. Examples of printer-encoders are disclosed incommonly-owned U.S. Pat. Nos. 6,848,616; 7,137,000; 7,398,054; and7,425,887 and U.S. Publication Nos. 2007/0216591; 2007/0262873;2008/0074269; 2008/0117027; and 2008/0238606 which are herebyincorporated herein by reference.

FIG. 1 illustrates an example of an RFID printer-encoder 120 that may beconfigured to print and/or encode a series or stream of media units 124.The printer-encoder 120 may include several components, such as aprinthead 128, a platen roller 129, a peeler bar 132, a roller 136, aribbon take-up spool 140, a ribbon supply roll 141, a transceiver 142, acontroller 145, and a RFID coupling device, such as a near-fieldcoupling device 150. The configuration of the printer-encoder 120 mayalso define a feed path 130, a media exit path 134, and a carrier exitpath 138.

As noted above, media units may include labels, cards, etc., that may becarried by a substrate liner or web 122. The web 122 may be directedalong the feed path 130 and between the printhead 128 and the platenroller 129 to allow for printing indicia onto the media units 124. Theribbon supply roll 141 may include a thermal ribbon (not shown forclarity) that extends along a path such that a portion of the ribbon ispositioned between the printhead 128 and the media units 124. Theprinthead 128 may heat up and press a portion of the ribbon onto themedia units 124 to print indicia on the media units 124. The take-upspool 140 may be configured to receive and spool the used ribbon.Printing in the manner described can be referred to as a thermaltransfer printing. Several other printing techniques may be usedincluding, but not limited to, direct thermal printing, inkjet printing,dot matrix printing, electro-photographic printing, laser, or the like.

After printing, the media unit web 122 may proceed to the media exitpath 134 where the media units may be removed from the web 122. Forexample, in one exemplary embodiment, pre-cut media units 124 may bepeeled from the web 122, to separate the media unit from the backing123, using the peeler bar 132 as shown. In other exemplary embodiments,a group of multiple media units may be peeled together and transmitteddownstream to an in-line cutter for subsequent separation (not shown).Various other known media unit removal techniques may be used, as willbe apparent to one of ordinary skill in the art.

In applications, such as the depicted embodiment, in which the mediaunits 124 are supported by a web 122, the web 122 may be guided along apath toward the carrier exit path 138 by roller 136 or other devices,once being separated from the media units. Techniques and structures forconveying or guiding the web of media units along the entire feed pathof the printer-encoder may be referred to as conveyance systems.

The transceiver 142 and the near-field coupling device 150 may beconfigured to communicate with a targeted transponder on a media unit bybeing controlled by, for example, a processor. The transceiver 142and/or the near-field coupling device may be controlled by hardwareand/or software configured processor, such that communication signals,for example to encode the transponder, may be provided via theprocessor. In some exemplary embodiments, a transponder that is affixedto a media unit 124 may be encoded as the transponder passes thenear-field coupling device 150 along the feed path 130.

The transceiver 142 may be configured to generate and transmit RFcommunication signals that are broadcasted by the near-field couplingdevice 150 located in close proximity to the media feed path 130 and thecorresponding media unit. For purposes of the present specification, thetransceiver 142 and the near-field coupling device 150 may be referredto collectively as forming at least part of a communication system. Thecommunication signals generated by the transceiver 142 or re-radiated bya passive transponder (or generated by an active transponder) may be inthe ultra-high frequency (UHF) band. However, some embodiments of thepresent invention may also be configured to operate using the variousother various frequency bands allocated for RFID communications, suchas, but not limited to, very high frequency (VHF), high frequency (HF),or the like. As explained in more detail below, the RFID interrogationsystem generates an electromagnetic field for the transponder activationover a mutual coupling link between the transceiver and a targetedtransponder of a media unit that is located within a predetermined area,referred to herein as either the encoding area, such that data may beread from and/or written to the transponder.

In general, a transceiver in a RFID system, such as the transceiver 142,can be a device configured to generate, process, and receive electricalsignals through the use of an antenna or, in close proximity, anear-field coupling device. One skilled in the art would appreciate thatsimilar devices such as readers, transmitters, receivers, ortransmitter-receivers may be used with or be part of this invention.Further, the term “transceiver” as used in the present application andthe appended claims refers to the devices noted above and to any devicecapable of generating, processing, or receiving electrical and/orelectromagnetic signals.

FIGS. 5 a through 5 d depict various exemplary embodiments of thenear-field coupling device 150 that may be utilized to manage atransceiver-transponder data communications. The near-field couplingdevice 150 may be utilized by, or otherwise in connection with atransceiver (not shown in FIGS. 5 a through 5 d). The near-fieldcoupling device 150 may include one or more terminated radiatingelements or conductive strips 530, 540 a-h. The conductive strips 530,540 a-h may be electrically connected to a port 500 (e.g., aninput/output port, RF port, etc.) and a terminating load 510. Theconductive strips 530, 540 a-h may be switchable conductive strips suchthat the conductive strips 530, 540 a-h may be connected to either theport 500 or the terminating load 510 through switching devices 520 a-h.

The port 500 may connect the transceiver to one or more conductivestrips (possibly through one or more switching devices). Further, theport 500 may be used to provide a signal to the conductive strips 530and 540 for contactless communication via the conductive strips. Theterminating load 510 may be connected to the one or more conductivestrips, possibly through one or more switching devices 520 a-h, at afirst terminal and may be grounded at a second terminal.

The near-field coupling device 150 may also include a dielectricsubstrate 550 and a ground plane 560. The dielectric substrate 550 mayhave a first surface and a second surface opposite the first surface.The conductive strips 530 and 540 may be affixed to the first surface ofthe dielectric substrate 550. The ground plane 560 may be affixed to thesecond surface of the dielectric substrate 550. The ground plane 560 mayhave various shapes. For example, the ground plane 560 may be generallyrectangular or circular and/or correspond to the overall shape of thenear-field coupling device or follow the shape of one or more conductivestrips. The ground plane 560 may be constructed of copper, gold, silver,aluminum or combination thereof, doped silicon or germanium, or anyelectrically conductive material. The general shape of the dielectricsubstrate 550 may vary between applications. For example, the dielectricsubstrate 550 may be a portion of a relatively larger printed circuitboard. The dielectric substrate 550 may be made or constructed fromvarious dielectric materials, including but not limited to, plastics,glasses, ceramics, or combinations such as Rogers materials, Isolamaterials, or woven glass reinforced epoxy laminate, commonly referredto as “FR4” or flame resistant 4. Moreover, air may be used as adielectric material. One skilled in the art would appreciate that theseor other materials may be used to achieve or utilize a specificdielectric constant. For example, a higher dielectric constant value orpermittivity may allow for a further decrease in the dimensions of thecoupler 50, including the thicknesses of the dielectric substrate andthe length of the conductive strips.

During encoding operations, as the electrical signal from thetransceiver passes through the one or more of the conductive strips, theconductive strips and the ground plane operate as coupling elements.Half-wavelength segments of the coupling elements may be defined suchthat the characteristic impendence of the coupling elements need not bematched or are mismatched from the terminating load impedance. As such,the near-field coupling device 150 may operate as one or more one-halfwavelength unmatched coupling elements, rather than operating as astanding wave radiating antenna or a magnetic field generating coil. Dueto the structure of the near-field coupling device 150, the passingcurrent in the conductive strips generates an electromagnetic fieldmostly concentrated in the near-field region of the near-field couplingdevice.

In particular and as illustrated in FIGS. 6 b, 7 a, and 7 c, the waveradiation generated by exemplary near field antenna embodiments of thepresent invention may create a near field effect that emanates from theedges of the one or more conductive strips as further described below.The near field effect may couple with a targeted transponder passingthrough the encoding area as described with respect to FIG. 2 furtherbelow. For purposes of the present invention and appended claims theterm “near field effect” refers to the one or more relatively localizedelectromagnetic fields that are also commonly referred to as “leaky”electromagnetic fields, as further described in “Leaky Fields onMicrostrip” L. O. McMillian et al. Progress in ElectromagneticsResearch, PIER 17, 323-337, 1997 and in commonly owned U.S. Pat. No.7,398,054 to Tsirline and U.S. Patent Publication Nos. 2005/0045724,2007/0262873, and 2007/0216591 to Tsirline et al., all of which arehereby incorporated by reference in their entireties. The effectiverange of couplers or antenna-couplers relying on such leakyelectromagnetic fields, referred to as near-field coupling devices, maybe limited because the fields degrade, at an exponential rate, withincreasing separation from the near-field coupling device. This limitedrange may reduce the likelihood that an electromagnetic field emanatingfrom a near-field coupling device will activate a transponder outsidethe intended encoding area.

For example, FIG. 2 depicts a simplified view of the feed path 130relative to the near-field coupling device 150. The near-field couplingdevice 150, as depicted in FIG. 2, includes conductive strips 530 and540, a dielectric layer 550, and a ground plane 560. The media unit 124travelling along the feed path 130 may include a transponder 220 and beaffixed to a web (not shown). The electromagnetic field generated by thenear-field coupling device 150 has a near-field strength and far-fieldstrength. As explained above, the near-field coupling device 150 may beconfigured to generate an electromagnetic field that has a strength inthe near-field that differs from a strength in the far-field. In someexemplary embodiments, the strength in the far-field may be too weak toactivate or communicate with the transponder, while the strength in thenear-field may be strong enough to activate the transponder. In otherwords, the near-field coupling device 150 may configured to generate anelectromagnetic field having a strength in the far-field too weak toactivate a transponder and a strength in the near-field sufficient toactivate a transponder.

As the media unit 124 and the transponder 220 move along the feed path130, the transponder 220 may arrive at a location where near-fieldenergy of the coupling device 150 is sufficient for a transponderencoding, i.e., the transponder may reach a location in which thetransponder is within the near-field of the electromagnetic fieldgenerated by the near-field coupling device and that field is sufficientto activate the transponder. The closest distance from any referencepoint, e.g., a tear bar, a printline, etc., along the feed path 130where a transponder initially is activated, such as point 210 in theillustrated embodiment, in the near-field of the coupling device 150 candefine a transponder “encoding starting distance.”

Further, according to various exemplary embodiments, an encoding range200 of the near-field coupling device may be defined as the startingdistance to a second point or location where a transponder encodingprocess is not longer possible, i.e., the location in which thetransponder gets an insufficient coupling with the near-field couplingdevice 150 and reaches a location in which the electromagnetic fieldstrength can not activate the transponder. The encoding range dependsboth on the characteristics of the near-field coupling device and theform-factor (i.e., physical dimensions) of the transponder. In someexemplary embodiments, the encoding range of the near-field couplingdevice 150 may be two to three inches. Together, the encoding startingpoint 210 and the encoding range 200, may define an encoding area wherecommunications between a transponder and a transceiver utilizing thenear-field coupling device can occur. In some embodiments, the encodingarea may be approximately equal to or less than the form-factor of thetransponder and, thus, the near-field coupling device is capable of onlyencoding one transponder at a time. The following parameters may definea printer encoding performance for a particular type of transponder: (1)the encoding starting point relative to a reference point within theprinter, such as the printhead; (2) the encoding range; and (3) the RFoperation power level necessary to ensure successful encoding of thetransponder.

In some applications, such as portable and compact systems (e.g., RFIDprinter-encoders), the near-field coupling device may be near or inclose proximity to a printhead. For example, the near-field couplingdevice may be close enough to the printhead and has a short encodingrange that at least a part of the encoding area for some types oftransponders overlaps the printhead (e.g., the encoding startingdistance relative to the printhead or a tear bar may be 0), which mayallow the system to encode the shortest possible labels or maintain theshortest pitch between labels. In other words, the system may beconfigured such that the system may print indicia onto the media unitwhile a transceiver is communicating with the transponder of the samemedia unit. The close proximity of the near-field coupling device andprinthead may be necessary or desirable in order to maintain overallcompact design of the system.

The type or category of transponders that may be used in connection withembodiments of the present invention may vary. FIGS. 3 a through 3 fillustrate examples of a first category or group of transponders thatmay be implemented in accordance with various aspects of the presentinvention. The exemplary transponders depicted in FIGS. 3 a through 3 dmay be referred to as long and narrow or long dipole-type transponders,due to the structure of the antennas of the transponders. The exemplarytransponders depicted in FIGS. 3 e and 3 f may be referred to as longand wide. FIGS. 4 a through 4 f illustrate examples of a second categoryor group of transponders that may be implemented in accordance withvarious aspects of the present invention. The exemplary transpondersdepicted in FIGS. 4 a through 4 f may be referred to as an item-level ora small loop-type transponders, due to the structure of the antennas ofthe transponders. Terms such as “long and narrow,” “long and wide,”“large”, and “small” are intended to indicate the relative size of thetransponders compared to an operational wavelength of the RFID systemand the transponder or compared to the transponder's relativedimensions. As examples, a large dipole-type may be about 3 inches long(i.e., the largest dimension of the dipole-type) and may be about0.3-0.6 inches wide, and a small loop-type may be about 1 inch long and1 inch wide.

In general, at the center of the operating band or spectrum (or at theoperating frequency) of the near-field coupling device, the portimpedance of one or more coupling elements that have a length of onehalf wavelength, or multiple thereof, is substantially equal to theterminating load impedance regardless of the characteristic impedance ofthe one or more coupling elements formed by or defined by the structureof the one ore more conductive strips and the ground plane. Therefore,in some embodiments, the length of the one or more coupling elements maybe one half wavelength, or multiple thereof (i.e., the length maysubstantially equal N*λ/2, wherein N may equal 1, 2, 3, 4, 5, . . . )and the terminating load may be configured to match the source impedancein order to substantially match the source impedance and the inputimpedance.

In some exemplary embodiments, the length of conductive strips 530 and540 may be determined based on the predetermined wavelength of acommunications signals to be used in an RFID system and the permittivityof the dielectric substrate. In this regard, the length of theconductive strips 530 and 540 may be half-wavelength (or half-wave), oran integer multiple of half-wave. In some exemplary embodiments, theconductive strips 530 and 540 a-h may be configured to exhibit theproperties of a half-wave dipole antenna.

The characteristic impedance of a coupling element may be defined by thecross-section structure of the coupling element. For embodiments inwhich the coupling element is a conductive strip and the ground plane,the cross-section may be mostly defined by the width and thickness ofthe conductive strip and a distance to the ground plane. Because it hasno or minimal influence on the port impedance of the near-field couplingdevice at the center operating frequency for embodiments having a lengthof one half wavelength or multiples thereof, the conductive strip may bedimensioned to achieve proper coupling with a targeted transponder,while the terminating load is configured to maintain an impedance matchbetween the near-field coupling device and the transceiver. For example,the width of the conductive strip may be decreased or increased toproduce a desired operating bandwidth of the near-field coupling device.In general, it is believed that the closer the impedance of the couplingelement is to the value of the terminating load (e.g., 50 Ohm) the widerthe bandwidth or the higher cut off frequency with some limit. Theimpedance of the terminating load may be modified to match the sourceimpedance (e.g., RF signal source impedance, transceiver impedance,system impedance).

The electromagnetic field pattern generated by the conductive strips maybe concentrated between the conductive strips and the ground plane, andas a result, the field strength above the conductive strips may berelatively low. When the total characteristic impedance of the couplingelements (formed be the one or more conductive strips and the groundplane) is lower than a terminating load then the maximum strength of themagnetic field component is located approximately at the center of thecoupling elements or the near-field coupling device and the maximumstrength of the electric field component is located at the edges of thecoupling elements or the near-field coupling device as illustrated inFIGS. 6 a and 6 b. FIG. 7 a illustrates a representation of the magneticfield strength adjacent to a coupling element with a totalcharacteristic impedance of the coupling elements is less than theterminating load. With respect to FIG. 7 a, note that the magnetic fieldintensity is maximized near or at the center of the coupling elements.

Although the relationship between the characteristic impedance of thecoupling elements and the terminating load impedance may vary, accordingto an exemplary embodiment of the invention, the total characteristicimpedance of the coupling elements may be lower than the terminatingload in order to maximize the magnetic field at the center of thecoupling elements. Further, terminating the coupling elements with aload that is substantially equal to the source impedance and greater orlower than the characteristic impedance of the coupling elements formswhat is known in the art as a “band-pass filter.” A band-pass filter isa device that is configured to transfer signal without degradingamplitude or power with a particular frequency or having a particularbandwidth. For example, the near-field coupling device may have anoperating frequency band of 902 MHz-928 MHz and a center operatingfrequency of 915 MHz. As another example, the operating frequency bandmay be from 870 MHz up to 953 MHz.

When the total characteristic impedance of the one or more couplingelements is greater than the impedance of the terminating load, themaximum strength of the magnetic field component can be at the edges ofthe coupling element or elements, and the maximum strength of theelectrical field component can be at the center of the coupling elementor elements. FIG. 7 b illustrates a graphical representation of relativestrengths of the electric and magnetic fields distribution along a halfwavelength coupling element having a characteristic impedance greaterthan the terminating load. Further, FIG. 7 c illustrates anothertwo-dimensional representation of the magnetic field strength ofadjacent to a coupling element with a characteristic impedance greaterthan the terminating load. With respect to FIG. 7 c, note again that dueto the characteristic impedance of the coupling element being greaterthan the terminating load, the magnetic field intensity is maximized ator past the ends of the coupling element. The distribution of electricand magnetic field components for a coupling element, such as microstripand stripline transmission lines is further discussed in detail in “UHFRFID Antennas for Printer-Encoders-Part 1: System Requirements”, HighFrequency Electronics, Vol. 6, No. 9, September 2007, pp. 28-39 which isauthored by one of the inventors of the present application and ishereby incorporated by reference in its entirety.

Accordingly, the selection of the ratio between the total characteristicimpedance of the one or more coupling elements of the near-fieldcoupling device 150 to the terminating load of a near-field couplingdevice 150, which can be referred to as the “impedance ratio,” may allowfor variations in the electric and magnetic field patterns formed by thenear-field coupling device 150. As such, by adjusting the impedanceratio, the location of the maximum electric or magnetic field can becontrolled. Various tests involving the encoding of transponders havedetermined that some transponders are activated or require less RF powerapplied to a near-field coupling device when proximate to a relativelystrong magnetic field component. In particular, loop-type transponders,such as those depicted in FIGS. 4 a through 4 c, and miniaturedipole-type transponders with a small loop element, such as thosedepicted in FIGS. 4 d-4 f, have been found to be sensitive to themagnetic field component. As such, adjustments to the location of themaximum magnetic field may be desirable based on the location of aloop-type or other type of transponder during, for example, an encodingprocess.

According to exemplary embodiments of the present invention, variousmeans for modifying the impedance ratio may be utilized. For example,the switching devices 520 may be configured to selectively connect anassociated conductive strip thereby introducing a change in the totalcharacteristic impedance of the connected coupling elements of anear-field coupling device 150. The term “connected” or “connect” asused herein refers to a conductive strip or a coupling element beingelectrically connected to the port 500 and the terminating load 510 suchthat the coupling element receives the signals from the transceiver viathe port 500 and broadcasts the signals. The switching devices 520 maybe RF switches with 50 Ohm impedance of Pole and each Throw switchingdevices capable of establishing or interrupting an electrical connectionwith a coupling element. In some exemplary embodiments, the switchingdevices 520 may be mechanical switches, transistors, PiN diodes, or thelike. The switching devices 520 may be controlled by a processor (e.g.,a software and/or hardware configured processor, including a fieldprogrammable gate array (FPGA)), a controller, other combinationallogic, or the like. In this regard, the processor may be configured toretrieve and execute program instructions stored on a computer-readablestorage medium for controlling the switching devices 520.

FIG. 5 a illustrates one exemplary embodiment of a near-field couplingdevice 150 with an adaptable field pattern based on a modification inthe impedance ratio. The near-field coupling device 150 of FIG. 5 a,includes two conductive strips 530 and 540 a that form two couplingelements 531 and 541 a. The characteristic impedance of each couplingelement, in isolation (i.e., when the coupling element is the onlycoupling element connected), may be equivalent. The equivalentcharacteristic impendence may arise as a result of, for example, theconductive strips 530 and 540 a having equivalent widths. The totalcharacteristic impendence of the connected coupling elements of thenear-field coupling device 150 of FIG. 5 a (i.e., the parallelcombination of the characteristic impedance of first and secondconnected coupling elements 531 and 541 a) may be modified by opening orclosing the switching device 520 a. The total characteristic impedanceof the connected coupling elements of near-field coupling device 150 mayhave a first value when the switching device 520 a is open, and a secondvalue when the switching device 520 a is closed. For example, the firstvalue may be greater than the terminating load 510 resulting in amaximum magnetic flux near the ends of the coupling element 531. Thesecond value may be less than the terminating load 510 resulting in amaximum magnetic flux near the center of the coupling elements 531 and541 a.

FIG. 5 b illustrates another exemplary embodiment of a near-fieldcoupling device 150 with an adaptable field pattern based on amodification of the impedance ratio. The near-field coupling device 150of FIG. 5 b, includes any number of conductive strips, which may includeconductive strips 530, 540 b, 540 c, and 540 d. Each of the conductivestrips together with the ground plane forms a coupling element 531, 541b, 541 c, and 541 d. The characteristic impedance of each couplingelement in isolation from each other may be equivalent. In exemplaryembodiments where the conductive strips are formed of the same substance(e.g., aluminum), the characteristic impedance of the coupling elementsmay be made equivalent by forming the conductive strips in a mannerwhere each of the conductive strips have the same dimensions. The totalcharacteristic impedance of one or more coupling elements may bemodified by opening or closing the switching devices 520 (e.g.,switching devices 520 a, 520 b, and/or 520 c). Therefore, the totalcharacteristic impedance of the connected coupling elements of thenear-field coupling device 150 may be variable based of theconfiguration of the switch devices 520. As such, the electric andmagnetic field patterns generated by the near-field coupling device 150of FIG. 5 b may include maximum magnetic field strength near orextending away from the ends of the coupling elements, a magnetic fieldstrength near the center of the coupling elements, or a maximum magneticfield strength located between the ends and the center.

FIG. 5 c illustrates another exemplary embodiment of a near-fieldcoupling device 150 with an adaptable field pattern based on amodification in the impedance ratio. The near-field coupling device 150of FIG. 5 c, includes two conductive strips 530 and 540 e and a groundplane 560 that together form two coupling elements 531 and 540 e. Thecharacteristic impedance of coupling elements 531 and 541 e, inisolation, from each other may be different. The difference incharacteristic impendence may arise as a result of, for example, theconductive strips 530 and 540 a having differing widths. The totalcharacteristic impedance of the connected coupling elements 531 and 541e of the near-field coupling device 150 of FIG. 5 c (i.e., the parallelcombination of the characteristic impedance of connected couplingelement 531 and coupling element 541 e) may be modified by opening orclosing the switching device 520 e. The total characteristic impedanceof the connected coupling elements may have a first value when theswitching device 520 e is in an open configuration (i.e., the conductivestrip 540 e is unconnected), and a second value when the switchingdevice 520 e is closed configuration (i.e., the conductive strip 540 eis connected). For example, the first value may be greater than theterminating load 510 resulting in a maximum magnetic field strength nearthe ends of the coupling element 531. The second value may be less thanthe terminating load 510 resulting in a maximum magnetic field near thecenter of the coupling elements 531 and 541 e.

FIG. 5 d illustrates another exemplary embodiment of a near-fieldcoupling device 150 with an adaptable field pattern based on amodification of the impedance ratio. The near-field coupling device 150of FIG. 5 d, includes any number of conductive strips, which may includeconductive strips 530, 540 f, 540 g, and 540 h, and a ground plane 560that together form coupling elements 531, 541 f, 541 g, and 541 h. Thecharacteristic impedance of each coupling element, in isolation, may bedifferent for each other. For example, the characteristic impedance ofeach coupling element, in isolation, may differ from each other becausethe widths of the conductive strips 530, 540 f, 540 g, and 540 h maydiffer. The total characteristic impedance of the connected couplingelements of the near-field coupling device 150 of FIG. 5 b (i.e., theparallel combination of the characteristic impedance of connectedcoupling elements 531, 541 f, 541 g, and 541 h) may be modified byopening or closing the switching devices 520 (e.g., switching devices520 f, 520 g, and/or 520 h). The near-field coupling device 150 may havea variable impedance ratio based of the configuration of the switchdevices 520. As such, the electric and magnetic field patterns generatedby the near-field coupling device 150 of FIG. 5 d may form a maximummagnetic field strength near or extending away from the ends of theconnected coupling elements, a magnetic field strength near the centerof the connected coupling elements, or a magnetic field strengthconcentrated more between the ends and the center.

FIGS. 5 a through 5 d illustrate exemplary near-field coupling devicesembodiments of the present invention that include generally linear andparallel conductive strips. As examples, the conductive material of theconductive strips may be copper, gold, silver, aluminum or combinationthereof, doped silicon or germanium, or the like. One of skilled in theart would appreciate that exemplary coupling devices of the presentinvention may also include non-parallel, non-linear, or tapered profilesof the conductive strips. For example, some embodiments of the presentinvention may include series of connected conductive strips. Forpurposes of the present specification and appended claims the term“non-linear profiles” refers to a segment of a conductive line or striphaving one or more turns or changes in direction. A non-linear portionmay have sharply defined turns to appear as a zig-zag type structure ormay have relatively smooth turns to appear as a wavy structure. Variousadditional exemplary near-field coupling devices employing zig-zag typestructures are described in commonly owned U.S. Pat. No. 7,398,054 andU.S. Patent Application Publication No. 2005/0045724 to Tsirline et al.,which are hereby incorporated by reference in their entirety. Variousadditional exemplary near-field coupling devices employing taperedprofiles are described in commonly owned U.S. Patent ApplicationPublication Nos. 2007/0262873 and 2008/0238606 both to Tsirline et al.,which are hereby incorporated by reference in their entirety.

Although, in illustrated embodiments of FIGS. 5 a through 5 d, thecoupling elements take the form of a microstrip. In other embodiments,the coupling elements may take the form of other transmission linestructures such as a stripline, a slotline or a finline. For example,various additional exemplary embodiments of the near-field couplingdevice may employ a stripline structure as further described in commonlyowned U.S. Patent Application Publication Nos. 2007/0216591 and2007/0262873 both to Tsirline et al., which are hereby incorporated byreference in their entirety. In yet other embodiments, the couplingelements may take the form of a planar waveguide, e.g., co-planar waveguide (CWG) 1000 as illustrated in FIG. 10. As another example, variousadditional exemplary embodiments of the near-field coupling device mayemploy a CWG structure as further described in commonly owned U.S.patent application Ser. No. 11/959,033 to Tsirline et al. filed on Dec.18, 2007, which is hereby incorporated by reference in their entirety.As further described in the above incorporated references, fornear-field coupling devices, the conductive strips and ground planes ofthe transmission lines or the CWG structure operate as a transmissionline, rather than operating as a standing wave radiating antenna ormagnetic field generating coil.

According to various embodiments of the present invention, the patternof the electromagnetic fields may be adjusted to correspond to theplacement, orientation, or other requirements of the targetedtransponder within the encoding area described with respect to FIG. 2.For example, as discussed above, within a printer-encoder, thetransponders 220 may be affixed to or embedded in the stream ofindividual media units 124, as shown in FIG. 2. However, the size andshape of the media units 124 or the placement of the transponders 220within the media units 124 may vary depending on the media unitconfiguration. Altering the pattern of the electromagnetic field bymodifying the impedance ratio, the near-field coupling device 150 canaccommodate different locations or orientations of the transponders 220and/or different types of transponders (e.g., dipole and loop), withoutsubstantially changing the encoding range 200 of the near-field couplingdevice 150 or requiring RF power adjustments.

FIG. 8 illustrates an exemplary placement of media units relative to anear-field coupling device 150 according to various embodiments of thepresent invention. The near-field coupling device 150 may be placedcross-wise relative to the feeding path 130 such that length of the oneor more conductive strips of the near-field coupling device areorthogonal to the feeding path 130. The alignment of the media units 124within a printer-encoder may be referred to as either edge justified(also referred to as side-justified) or center-justified. FIG. 8illustrates an example of an edge justified system, and in particular aleft edge-justified system. Further, the web to which the media unitsare affixed may have a narrow width, such as, for example, less than 6inches. In some embodiments, the width of the web may be 2 inches. In anedge justified system, the media unit 124 and, thus the transponder 220may be positioned near or aligned with the edge of the near-fieldcoupling device 150. In this example, the media unit 124 and thetransponder 220 are positioned near the left side of the near-fieldcoupling device 150. As such, a near-field coupling device 150configured to have maximum magnetic field strength near the edges of thenear-field coupling device may be desirable, particularly since thetransponders 220 of FIG. 8 may be representative of loop-typetransponders, such as those illustrated in FIGS. 4 a through 4 c, whichrespond favorably to stronger magnetic fields. Accordingly, theswitching devices of the near-field coupling device may be configuredsuch that the total characteristic impedance of the connected couplingelements of the near-field coupling device may be greater than theimpedance of the terminating load.

FIG. 9 illustrates an example of a center justified system or a centerjustified transponder positioning system. In a center justified system,the media unit 124 and thus, the transponder 220 may be positionedproximate to the center of the conductive strip of the coupling device150. As such, by controlling the switching devices of the near-fieldcoupling device 150 the impedance ratio may be modified. In someembodiments, a total characteristic impedance of the one or moreconnected coupling elements that is greater than the impedance of theterminating load may be sufficient to communicate with a centerjustified transponder, such as the long and narrow or large dipole-typetransponders, such as those illustrated in FIGS. 3 a through 3 f, whichmay be represented by the transponder 220 of FIG. 8, even though themagnetic field maximums may be near the edges of the near-field couplingdevice 150. However, a near-field coupling device having a totalcharacteristic impedance of the one or more connected coupling elementsthat is less than the impedance of the terminating load may also be usedto communicate with a center justified transponder. Therefore, in acenter-justified system processing long and narrow, and largedipole-type transponders, the electric and magnetic field componentsfrom the coupling device may be optimally aligned with the center of thetransponder to facilitate a strong coupling and, thus, reliablecommunication between the transponder and the transceiver through thecoupling device. In some instances, a long and narrow, or largedipole-type transponder may be large enough relative to the couplingdevice that even in an edge justified system, the transponder may beclose enough to the center of the conductive strip not to make asignificant difference in a near-field coupling device's ability tocommunicate with the transponder in the edge-justified system comparedto a center-justified system.

Another aspect of the present invention is a method of modifying theelectromagnetic field distribution or pattern of a near-field couplingdevice 150 for a printer-encoder to a particular media unitconfiguration. The method includes loading the printer-encoder 120, asshown in FIG. 1, with a web 122 of media units 124 having embedded orattached transponders and advancing at least one media unit 124 to theencoding area 200, as shown in FIG. 2. Various methods for altering theproperties of the near-field coupling device 150 may be utilizedaccording to exemplary embodiments of the present invention.

In one exemplary embodiment, the printer-encoder 120 may include asensor or other means for detecting and discriminating the media unittype (e.g., media units with loop-type or large dipole-typetransponders). In some exemplary embodiments, the transceiver maycommunicate, e.g., via a second or supplementary antenna, with aspecial, additional, identification transponder, for example, on theroll of the media or the first transponder of the media, to determinethe media unit type. Further, the printer encoder 120 may include asensor that may identify the justification or cross-wise position of themedia units. In some embodiments, a processor included inprinter-encoder 120 may be configured to detect or receive data orinformation regarding the media unit type and justification (e.g.,transponder cross-wise position and other transponder placementparameters). In some exemplary embodiments, a user may enter the mediaunit type and the justification (e.g., transponder cross-wise positionand orientation) into the printer-encoder via a user interface to bereceived by a processor. Based on the media unit type and thejustification, the processor may be configured to modify the impedanceratio of the near-field coupling device 150 by controlling the switchingdevices. The impedance ratio may be modified such that a desirableelectromagnetic field pattern is generated.

In another exemplary embodiment, in order to configure the near-fieldcoupling device to the loaded media unit's configuration, or morespecifically to the orientation of the transponder on the label of themedia unit and within the encoding area, a tuning cycle may be executed.As a sample media unit having a transponder may be in the encoding area,a transceiver may generate a test signal and transmit the signal throughthe near-field coupling device. The processor may command the switchingdevices to execute a number of possible combinations by energizing orconnecting the conductive strips. In order to determine a “preferredradiating set” of connected or unconnected conductive strips, eachcombination may be monitored to determine what combinations of connectedor unconnected conductive strips, referred to herein as “radiatingsets,” allow for a reliable encoding process for the targetedtransponder. Furthermore, the processor may regulate the power level ofthe signal to determine what combination provides a reliable encodingprocess at the lowest power level. The combination that results in areliable encoding process at the lowest power level may be determined tobe the preferred radiating set for that particular media unitconfiguration. “Reliable encoding process” as used within thisspecification and the appended claims means the ability for thetransceiver through the near-field coupling device to effectivelycommunicate with the targeted transponder through the electromagneticfield pattern created by the near-field coupling device, whileminimizing inadvertent communication with untargeted transponders andlowering a bit error rate.

Once the preferred radiating set is known, that radiating set may beconfigured for that media unit configuration and the printer-encoder mayproceed with the normal processing and encoding (e.g., write and readaction) of the media units. The timing or frequency of executing atuning cycle may vary. For example, once the preferred radiating set isknown for a particular media unit configuration, data and informationfor that preferred radiating set may be stored within a memory deviceincluded within the printer-encoder. When that particular media unitconfiguration is used, an operator may be able to enter thatconfiguration information into the printer-encoder through a keypad (notshown) allowing the processor to set the preferred combination withoutre-executing a tuning cycle. Also, the processor may be programmed torun a tuning cycle after a certain event such as the turning on of theprinter-encoder, the loading of media units, the passage of certainamount of time, or after predetermined number of media units have beenprocessed.

Many modifications and other embodiments of the invention set forthherein will come to mind to one skilled in the art to which thisinvention pertains having the benefit of the teachings presented in theforegoing descriptions and the associated drawings. Therefore, it is tobe understood that the invention is not to be limited to the specificembodiments disclosed and that modifications and other embodiments areintended to be included within the scope of the appended claims.Although specific terms are employed herein, they are used in a genericand descriptive sense only and not for purposes of limitation.

1-20. (canceled)
 21. A near field coupler system comprising: atransceiver; and a near field coupler in electrical communication withthe transceiver, the near field coupler configured to transmit wirelesssignals to a targeted transponder, the near field coupler comprising: adielectric substrate having a first surface and a second surface; aground plane adjacent to the second surface of the dielectric substrate;radiating elements disposed on the first surface of the dielectricsubstrate, wherein: the radiating elements are coupled to the groundplane through one or more terminating resistors; a first radiatingelement of the radiating elements defines a first impedance; a secondradiating element of the radiating elements defines a second impedance;the first impedance, in isolation, is different from the secondimpedance, in isolation; and at least one switching element coupled toeach of the radiating elements, wherein the at least one switchingelement is: configured to be in electrical communication with thetransceiver; and configured to selectively activate one or moreradiating elements among the radiating elements to provide selectivewireless communications between the transceiver and the one or more ofthe radiating elements to communicate with the targeted transponderhaving an unknown orientation relative to the radiating elements. 22.The near field coupler system of claim 21, wherein the at least oneswitching element is further configured to selectively activate the oneor more radiating elements to minimize inadvertent communications withtransponders other than the targeted transponder while enabling areliable encoding of the targeted transponder.
 23. The near fieldcoupler system of claim 21 further comprising a processor configured todetermine a transceiver power level required to effectively communicatewith the targeted transponder.
 24. The near field coupler system ofclaim 23 further comprising a non-transitory storage device used tostore data associated with the transceiver power level, wherein the datais accessed to communicate with subsequent transponders arranged in theunknown orientation.
 25. The near field coupler system of claim 23,wherein the transceiver power level is a highest transceiver power levelpossible without allowing inadvertent communication with transpondersother than the targeted transponder.
 26. The near field coupler systemof claim 23, wherein the transceiver power level is the lowesttransceiver power level required to effectively communicate with thetargeted transponder.
 27. The near field coupler system of claim 21,wherein the at least one switching element is comprised of a pluralityof switches and wherein the number of switches is equal to or less thanthe number of radiating elements.
 28. The near field coupler system ofclaim 21 further comprising a processor configured to determine apreferred configuration of the at least one switching element toeffectively communicate with the targeted transponder while minimizinginadvertent communications with transponders other than the targetedtransponder and while enabling a reliable encoding of the targetedtransponder.
 29. The near field coupler system of claim 28 furthercomprising a non-transitory storage device used to store data associatedwith the preferred configuration of the least one switching element tolater access the data to communicate with subsequent transpondersarranged in the unknown orientation.
 30. The near field coupler of claim21, wherein the radiating elements include at least three radiatingelements and each radiating element is a conductive strip disposed onthe first surface of the dielectric substrate.
 31. The near fieldcoupler system of claim 21 further comprising a printhead configured toprint indicia upon a media unit associated with the targetedtransponder.
 32. The near field coupler system of claim 21 furthercomprising a sensor configured to identify a preferred configuration ofthe at least one switching element to effectively communicate with thetargeted transponder while minimizing inadvertent communications withtransponders other than the targeted transponder and while enabling areliable encoding of the targeted transponder.
 33. The near fieldcoupler system of claim 21 further comprising a sensor configured toidentify the unknown orientation of the targeted transponder.
 34. Amethod of tuning a near field coupler system comprising: transmitting acommunication signal from a transceiver to a near field coupler, thenear field coupler comprising radiating elements and at least oneswitching element, wherein: a first radiating element of the radiatingelements defines a first impedance; a second radiating element of theradiating elements defines a second impedance; the first impedance, inisolation, is different from the second impedance, in isolation; and theat least one switching element is configured to provide selectiveelectrical communication between the transceiver and one or more of theradiating elements among the radiating elements to define multipleradiating configurations for broadcasting wireless signals into atransponder operating region; positioning a targeted transponder withinthe transponder operation region, wherein the targeted transponder isarranged in an unknown orientation; broadcasting wireless signals intothe transponder operating region; determining a selected radiatingconfiguration of the plurality of radiating configurations, wherein theat least one switching element defines the selected radiatingconfiguration and wherein the selected radiating configuration providesselective wireless communications between the transceiver and the one ormore of the radiating elements to communicate with the targetedtransponder having the unknown orientation; and storing data associatedwith the selected radiating configuration.
 35. The method of claim 34further comprising determining a power level for each of the multipleradiating configurations that accommodates a reliable encoding of thetargeted transponder, wherein determining the selected radiatingconfiguration is based on the selected radiating configuration having alowest power level among the power levels for each of the multipleradiating configurations.
 36. The method of claim 34 further comprisingdetermining a power level for each of the multiple radiatingconfigurations that accommodates a reliable encoding of the targetedtransponder, wherein determining the selected radiating configuration isbased on the selected radiating configuration having a highest possiblepower level without allowing inadvertent communication with transpondersother than the targeted transponder.
 37. The method of claim 34 furthercomprising accessing the data and utilizing the selected radiatingconfiguration for subsequent transponders arranged in the unknownorientation.
 38. The method of claim 34 further comprising: positioninga new transponder within the transponder operation region, wherein thenew transponder is arranged in an orientation different than the unknownorientation; determining a new radiating configuration of the pluralityof radiating configurations, wherein the at least one switching elementdefines the new radiating configuration and wherein the new radiatingconfiguration provides selective wireless communications between thetransceiver and one or more of the radiating elements to communicatewith the new transponder having the new orientation; and storing newdata associated with the new radiating configuration.
 39. The method ofclaim 34 further comprising printing indicia upon a media unitassociated with the targeted transponder.
 40. The method of claim 34further comprising identifying a preferred configuration of the at leastone switching element to effectively communicate with the targetedtransponder while minimizing inadvertent communications withtransponders other than the targeted transponder and while enabling areliable encoding of the targeted transponder.
 41. The method of claim34 further comprising identifying the unknown orientation of thetargeted transponder.